Control system for ovens



y 3, 1965 H. s. BEACH ETAL 3,194,227

CONTROL SYSTEM FOR OVENS Filed Sept. 5, 1962 ZO El \l I I I 1 IST TEN!- THERMO PROGRAM COOKING THERMO CLOCK H. STANLEY BEACH BY Rossm' L. Mom/s United States Patent 3,194,227 CONTROL gYSTiEM 1 9R GVENS Herbert Stanley Beach and Robert 1.. Morris, Kaniralree, 1th, assignors, by mesne assignments, to Geo. D. Roper (Iorporation, Kankalree, Iii, a corporation of Delaware Filed Sept. 5, 1962, Ser. No. 221,569 7 (Zlaims. ((31. 126-39) Thisinvention rel-ates generally to ovens and is more particularly concerned with a control system for igniting the broiler burner in a single cavity gas oven.

Customarily, for normal baking in a gas oven it is desirable to have the burner at the bottom of the oven chamber or cavity in order to achieve even distribution of heat by ,the circulating convection currents. Where it is desirable to use the same oven cavity for broiling purposes it is necessary to have a separate burner at the top of the cavity. In the past, where this has been done, it has been necessary to control the broiler manually and to light it with a match. This is due to the fact that the products of combustion of the lower oven burner will ordinarily extinguish the pilot flame in the upper portion of the broiler, and thus allow pilot gas to accumulate in the oven cavity and create an unsafe condition.

Accordingly, the primary aim of the present invention is to provide a control system for a single cavity gas oven which will automatically light a pilot for igniting the flame on a broiler burner in the top of the cavity when operation of the broiler is selected. It is a more particular object to provide such a control system which precludes the flow of gas to the broiler burner until after a flame has been established adjacent the broiler burner to insure that no gas accumulates in the cavity before the burner lights.

It is another object to provide a control system for a single cavity oven in which the supply of gas to the broiler pilot flame is turned off automatically when the oven burner is selected. It is a related object to provide such a system in which only a single control is required to select either oven or broiler operation and to establish or ex- .tinguish the broiler pilot flame according to whether or not the broiler burner is selected.

Another object is to provide a control system of the above type which is safe and dependable in operation and which will automatically turn oh" the pilot igniter if, after a predetermined period, no flame has been established adjacent the broiler burner. A further object is to provide a broiler pilot which includes a runner tube so that the pilot igniter may be located away from the intense heat of the broiler burner.

It is also an object to provide a control system as characterized above which is inexpensive to manufacture and which is easy to maintain and service after it has been installed within the oven chamber. Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

FIGURE 1 is a diagram showing an oven cavity in cross section including a broiler and control arrangement constructed in accordance with the present invention;

FIG. 2 is a schematic diagram of a gas distribution sys tem and electrical control circuit of the present invention.

While the invention will be described in connection with a preferred embodiment, it will be understood that we do not intend to limit the invention to that embodiment; on the contrary, we intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning now to the drawings, FIGURE 1 diagrammatically illustrates an oven cavity to which the present invention has been applied. The insulated housing indicated 3,l%,22.7 Patented July 13, 1965 "ice at 10 is provided with the usual shelf supports 11 for mounting shelves (not shown). For ordinary baking a regular oven burner 12 occupies a position at the bottom of the cavity with gas-air mix being supplied through a tube 13. The oven burner is ignited by a standing pilot 14 which controls a flame switch 15.

At the top of the oven cavity a broiler burner 16 is provided which receives gas-air mix through a tube 17. This burner may, for example, be of the type covered in the co-pending application Ser. No. 214,655, filed August 3, 1962, now abandoned, to which reference is made. This type of burner is distinguished by a downwardly angled pattern of flames 13 Well suited for broiling purposes. Arranged directly above the burner 16 is a draft plate 19, with the products of combustion being vented through a vent 20.

To supply gas to the burners 12 and 16, the oven is provided with a gas manifold 22. A main gas supply line 23 having a' shut-01f valve 24- feeds an over burner supply line 26 and'a broiler burner supply line 27 which are respectively connected to the burner tubes 13, 17. For controlling the passage of gas to the burners, the supply lines at, 27 are respectively provided with solenoidoperated valves 28 and 29.

For regulating the operation of the solenoid valves 23, 29 and thus to control the gas supplied to either of the burners 12, 16 and the operating temperature in the oven, an electrical control circuit is provided. A program cook- 'ing clock 30 is connected to a hot, wire 31 of an electrical outlet (not shown). The cooking clock 30 includes the usual timing motor and control knobs and is also provided with two output terminals 32 and 33 connected respectively to a high temperature thermostat 34 and a low temperature thermostat 35 which are connected to a control lead as. The control lead 4t? has branch lines 41 and 42 connected respectively to the two solenoid valves 28, 29.

Selection of either the oven burner 12 or the broiler burner 16 is made by a selector switch 45 which includes an operating knob 46 preferably located on the control panel of the oven. The switch 45 has a switch blade 47 connected to the common terminal 5th of an electrical outlet. Fixed contacts 4% and 49 are connected to the bake solenoid and broiler solenoid so that one of these two solenoids may be selected for operation.

In order to light the oven burner 12, the pilot burner 14 has a continuous or standing flame provided fuel by a pilot supply line 51 connected to the manifold 22 through a filter 52. It will be understood that when gas is admitted to the oven burner 12, the flame from the oven pilot 147 will ignite the burner. To insure that no gas escapes from the oven burner 12 when there is no flame on the pilot 14, the oven flame switch 15 has a sensing element 54 disposed to detect the presence of a flame on the oven pilot. The flame switch 15 has normally open contacts 55 and as which close when the sensing element 54 detects a flame, the contacts thereby completing a circuit through wires $7 and 53 forming part of the circuit ror actuating the oven solenoid 28. Therefore, if there is not pilot flame, the oven burner 12 will not operate and gas from the oven burner will not accumulate in the oven.

In accordance with the present invention, a control .system is provided for automatically supplying gas to, and

valve 59 is coupleditothe .gizingthe broiler solenoid, valve '29. .br'oiler flame switch 65;isgprovided with a contact :71 normally closed with contact 67'for energizmgthe age" controls the selector switch45 so that gas is delivered to the broiler pilot only'when the switch '45 is turned to .broil .toenergize the broiler solenoid valve. 29: More- .over, an electric-a1.igniter or glow-coil 62 is arranged to be energizedrby the selector switch 45to ignite the broiler (pilot 51 which is coupled to a runnerutube-fifa" same operated knob 4 6 .which disposed adjacent the broiler burner-16. The rnnnertube 63 hasa plurality of gas .ports 64 along which the flame from .the pilot burner 61 is successively propagated to 1 carry the flame to the broiler burner 16.

f It will be. appreciated that the broiler pilot 61 does not have a continuous flame such as the standing flame of the. oven pilot 14 because the flame on thebroiler pilot located in the top of the oven cavity would be ex; tinguished by the products of combustion :each time? the oven burner 12 is operated, Therefore, the broiler pilot' 7 61-.is supplied with gas and ignited eachztime the broiler burner '16 is usedand shut oif when theoven burner 12 is selected sothat-gasescaping, from thetpilot newer accumulateiin the oven and cause an unsafe condition. Pursuant to another feature of the invention, :a broiler flame switch 65 having a sensing element 66;isdisposed to detect a flame at thejend of the runner tube 63 adjacent. the broiler burner 16 so that no gasv is admitted to the .broiler burneruntiliits ignition is insured. The broiler 'j'flame switch 65, similar to the oven flame switch 15, in} 1 cludes normally open contacts 67 and 68 which close when thesensing element 66detects a flame. The contacts67, 68 complete a circuit through Wires 69 and 70 for enerniting coil 62.

For energizing the igniting coil 62, a transformer @75 having a primary winding 76 and a secondary winding 77 is coupled with the primaryin series to the ,fhot input. "line 31' of the oven and the flame switch contact'illiaby 'wires 78 and 79, respectively. The transformer secondary 77 is'connected directly to the igniting coil 62. Since the flame switch contacts 67,71 are normally .closed 'whenthere; is no'flame on the runner tube 63, turning the selec: tor knob 46 to ,broil completes a circuit through the transformer primary 76 and'energizesthe secondary cir;-'

cuitwto the igniting coil 62.1 As mentioned above, move ment of the knob 46 to broil also opens/the broiler 7 In addition, the

pilot supply valve 59 to allow. gas to flow to thejbroiler V pilot:61 where the pilot 'gas is' ignited by the .coil. 62.

In .the preferred embodiment, the elongated runner tube V 63 which carries the flame from the broiler p'ilot' 61 ;to the burner 16 allows the igniting coil 62 to be positioned away from the intense heat of thejbroiler flame 18. 'In addition, the sensing element .66 is positioned so that. it;

- escapes into the top. of. 'the ovencavityv k As a built-i safety feature, if thegpilot' flame does noti ireach theend 'ofthe runner tube 63;,jcontactsg67, '71;will not open and contacts 67:68- will not: iclcse; :Thus, the p a solenoid. valve 29.,will 'not. open, and after zapre-detr-L V inined intervaltheiva'rp zswitc'h 8 iwill opendue to the, "1

does not actuate the broilerflame switch 65 until the' pilot flame has been propagated at the endof the runner 'tube 63*adjacent the broilerburner :16 where ignition of;

the broiler flame is insured. Thus,.if for some reason no I flame is established at the end of the runner tube 63, the contacts'67, 68 will not close to energize the:;broiler sole-i mid valve 29 and gas will not rcaclithe broiler, burner 16 to create an unsafe condition. 7 To prevent theignitingcoil 62 from burning out, if.

the pilot 61 does not lighttor if the flame switch 65 does I not detect a flame on the'runner' tube 63,21 safety shut- .ofiswitch'fiSis connected in serieswith the tra'ris'frfrier' Inthe preferred'embodiment, the safety switch 85 is an integral warp switch having a bin. [metal switch blade 86 adjacent a heating element 87 primary winding 7 6.

contained within.;the transformerf75.. The heating 'element 87 1's preferably timed so that it'warps the switch blade 86 atO open the.transformer primary circuit a pre- 1 determined interval after the igniting coil 62 is energized.

a the present case the safety switch is timed for 'a threeminute interval. Thus if the transformer remains energized 'by the flame switch 165, the safety'switch 85.

, will automatically. .de-energizei the igniting coil {621 three V 1 minutes after'ithas beenenergized-andaccordingly will" greatly prolong the life'of' the .ignitingjcoilg. 7

Operation ofthe: oven control system-may now;be described as follows. If thejoven 'isjto be used for baking, the control knob 461s turned. to ""ba'kei closinggswitcht 7 blade 47 against contact; 48" which energizes. thefoven solenoid valve 28 provided that thereis'ja flame in o-the oven pilot 14. Gasnovv flows to the oven burner, 12 I, where. it isignitcd'bythe pilotzfla'me, -At this'tirne the. flow of gas throughi the solenoid valve isregulated by; i the program'cooking cloickStl, and ithegfirst Tandsecondj temperature thermostats 34, '35 %until the, solenoid :valye I 28 is automatically or manually shutotfat the'end ofrth'e rbaking'pe'riod. During the baking period it'will be .ob-

viousi that the heat'providedby the pilo trl tj and'the burner 1 12 on the sensing element 54'willkeep the fiame'rswitch contacts. 55, 55, closed. It Willi alsobe .apparent that if; i V a there is no pilot flame when the[control knob 451 is turned J to,rbake the contacts 55, 56 will be open and theisole :7 I

"noid valve 23: will'not be energized; V

When it is desired to use theoven forb 'oilin portion of gas'flowing'to;the"-pilot1 61lpasises thr'ough the f68 are closed to: energize the' sQlenOid-jZ One or more broiling fsequcncszmaylbe nitiated in out, it will be re-ignitedl'as soon as thejgsensingielement detects no flame, on the runnertubeffi or broiler burner 16. However, when the controlknob 4 6- isturnediaway from, the i broil position both the solenoidv'alve and-the pilot, control valve '59 are closed thereby: insuring that no gasf succession, since, even if ltheii pilot fl ame go heating of the element 87 andthej blade 86 and breakfthef cncuitto the transformer primary .76 ;thereby de encrg'iz-= 'ing the transformer secondary?hndignitihgQcoil 62,1;

Afterthe cause of the failure .of afiaime togreachtthe end a of the, runner tube' 1;63i has been ;determined,- thej warpswitch 35 maybe manually rese't and operation resumed;

an oven burner; :12 and a .broileryhurner iii-in" a single cavity gas ,oven.1 No t.only doesthisi'reduce; ihi size} and j. 5 j

cost of conventional stove-oven:combinations,"but it also a greatly .facilitatesthe use 'of {single cayit y-gas ovens in f L built=ininstallationa In additiomthe control system, is

safe and dependableand, inftheeve'nt.thatjsome diflicultyl;

should raise,vit'mayib c easily 8 vicedwi We claimasour'inventionr,

V "thelconw trol knob 46 is turned to, broilfwhichenergizes, the. 1 ,7 transformer primary 76 inTa circuitiincluding the selector 1 switchblade; 47.," contact 549 and normally closed icontacts "67,71 of the'broiler flameswitch165;; At-thec-same time, the; broiler pilot "supply valve-'591Fis opcncd; to admitigas T fto' the broilerpilot til where 'it'is ignited'by-thc igniting. t

coil 62 energized by the.transforrneii secondairy 77. "A

It will now, be, appreciated that gthe 1present2invention 7 I provides a control system for automatically igniting'both' '1. In a single cavity gas oven, the combination com, prising, a gasmanifold; an. oven burner glocated Yatth'e 1 bottom of the cavity. and a broil bur en-located. the.- top ;of the eavny, .meansi including-first and second sole jnoid valves "for 'regulating ftheesupply fof gasffrom the manifold to the respective burners, a pilot supply line coupled to said manifold, a broiler pilot communicating with said supply line, said broiler pilot located adjacent said broiler burner and having an electrical igniting means therefor, first circuit means for said igniting means, selector means having a plurality of operative positions for independently energizing said solenoid valves, other circuit means coupling the selector means in separate series circuits with the respective solenoid valves, said selector means being so constructed and arranged that when it is in one position the first solenoid valve for said oven burner is activated and so that when it is in another position said circuit means for said igniting means is activated, a pilot gas valve interposed in said pilot supply line between the manifold and the broiler pilot and coupled to the selector means for operation therewith so that the flow of gas to said broiler pilot is precluded when said selector is in said one position and so that the flow of gas to said broiler pilot is permitted when said selector is in said other position.

2. The combination defined in claim 1 including switching means interposed between said first circuit means and said other circuit means for said second solenoid valve for said broiler burner, said switching means operable upon actuation thereof for energizing said second solenoid valve and for deenergizing said igniting means after a flame is established on said broiler pilot.

3. The combination defined in claim 2 including means including a standing pilot burner coupled to said manifold for igniting said oven burner when said selector means is in said one position, said pilot gas valve for said broiler pilot being turned off when said selector means is in said one position to thereby prevent the extinction of said broiler pilot by the products of combustion of said oven burner incident to operation of said oven burner.

4. The combination defined in claim 1 including thermostat means connected in series with said oven and broil solenoids for selectively modulating the flow of gas therethrough in accordance with the temperature in said cavity and the temperature selected at said thermostat.

5. The combination defined in claim 1 including a transformer, said igniting means coupled in series with the secondary of said transformer, a limit switch connected in series with the primary of said transformer, said limit switch being timed to open a pre-determined interval after said igniting means is energized.

6. In a single cavity oven, the combination comprising, a gas manifold, an oven burner located at the bottom of the cavity and a broiler burner located at the top of the cavity, means including oven and broiler solenoid valves for regulating the supply of gas from the manifold to the respective burners, a pilot supply line coupled to said manifold, a broiler pilot communicating with said supply line, said broiler pilot located adjacent said broiler burner and having an electrical igniting means therefor, first circuit means for said igniting means, selector means for independently activating the oven solenoid and broiler solenoid and having bake and broil positions, other circuit means coupling the selector means in separate series circuits with the respective solenoid valves, said selector means being so constructed and arranged that when it is in the bake position the oven solenoid is activated and so that when it is in the broil position, the circuit means for said igniting means is activated, a flame detector switch associated with said pilot and operable to shift between first and second positions upon being heated by a flame on the pilot, a pilot gas valve in said pilot supply line and coupled to the selector means for operation therewith to allow the flow of gas from the manifold to the pilot when said selector means is in the broil position, said flame detector switch closing said circuit for said igniting means when in said first position, and closing said other circuit means for said broil solenoid when in said second position so that when the selector means is turned to the broil position gas is supplied to the pilot and the igniter is turned on and so that upon subsequent heating of the fiame detector switch by a flame on the pilot the igniter means is turned off and the broil solenoid is turned on for regulating the supply of gas to the broiler burner.

7. The combination defined in claim 6 including a runner tube for said broiler pilot, said runner tube having one end thereof adjacent said broiler burner and the other end thereof remote therefrom, said pilot supply line communicating with said other end of said runner tube, said flame detector switch being located adjacent said one end of said runner tube, and said igniting means being located adjacent said other end of said runner tube remote from said broiler burner and away from the intense heat generated by said broiler burner incident to operation thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,079,504 5/37 Hobson 23615 2,395,666 2/46 Kaufmann l58126 2,823,741 2/58 Thornbery 158-13l X 2,983,314 5/61 Geldhof et al 158125 3,033,463 5/62 Doner et al. 2361 FOREIGN PATENTS 792,930 4/58 Great Britain.

JAMES W. WESTHAVER, Primary Examiner. 

1. IN A SINGLE CAVITY GAS OVEN, THE COMBINATION COMPRISING, A GAS MANIFOLD, AN OVEN BURNER LOCATED AT THE BOTTOM OF THE CAVITY AND A BROILER BURNER LOCATED AT THE TOP OF THE CAVITY, MEANS INCLUDING FIRST ANS SECOND SOLENOID VALVES FOR REGULATING THE SUPPLY OF GAS FROM THE MANIFOLD TO THE RESPECTIVE BURNERS, A PILOT SUPPLY LINE COUPLED TO SAID MANIFOLD, A BROILER PILOT COMMUNICATING WITH SAID SUPPLY LINE, SAID BROILER PILOT LOCATED ADJACENT SAID BROILER BURNER AND HAVING AN ELECTRICAL IGNITING MEANS THEREFOR, FIRST CIRCUIT MEANS FOR SAID IGNITING MEANS, SELECTOR MEANS HAVING A PLURALITY OF OPERATIVE POSITIONS FOR INDEPENDENTLY ENERGIZING SAID SOLENOID VALVES, OTHER CIRCUIT MEANS COUPLING THE SELECTOR MEANS IN SEPARATE SERIES CIRCUITS WITH THE RESPECTIVE SOLENOID VALVES, SAID SELECTOR MEANS BEING SO CONSTRUCTED AND ARRANGED THAT WHEN IT IS IN ONE POSITION THE FIRST SOLENOID VALVE FOR SAID OVEN BURNER IS ACTIVATED AND SO THAT WHEN IT IS IN ANOTHER POSITION SAID CIRCUIT MEANS FOR SAID IGNITING MEANS IS ACTIVATED, A PILOT GAS VALVE INTERPOSED IN SAID PILOT SUPPLY LINE BETWEEN THE MANIFOLD AND THE BROILER PILOT AND COUPLED TO THE SELECTOR MEANS FOR OPERATION THEREWITH SO THAT THE FLOW OF GAS TO SAID BROILER PILOT IS PRECLUDED WHEN SAID SELECTOR IS IN SAID ONE POSITION AND SO THAT THE FLOW OF GAS TO SAID BROILER PILOT IS PERMITTED WHEN SAID SELECTOR IS IN SAID OTHER POSITION. 